Convertible duplex simplex printing telegraph system



J. N. LOOP June 14', 193s.

CONVERTIBLE DUPLEX SIMPLEX PRINTING TELEGRAPH SYSTEM Filed Apil 9, 1956 JVSN S mw m\\ ww Ww. /w

Patented June 14, 1938 loira simplified circuit for automatic printing tele- UNITED.. STATES PATENT OFFICE CNVERTIBLEDUPLEX SIMIPLEXv PRINTING TELEGRAPH SYSTEM Joseph N. Loop, Washington, D'. Application April 9, 1936,`Serial No. 73,525

17 Claims.

My invention relates broadly to printing telegraph` systems and more particularly to a convertible diierential duplex-simplex printing A,telegraph system. One of the objects of my invention is to provide' a system whereby automatic printers may be operated either duplex or simplex at the election of the operators.

Another object of my invention is to provide graph systems which may be operated through the usual concentrator boards either duplex or simplex with a simple switching means for determining either condition of operation of the system.

Still another object of my invention is to provide a balanced circuit arrangement for a printing telegraph sys-tem by which either duplex or simplex operation may be effected without dis-v turbing the balanced operation of the circuit.

A further object of my invention is to provide."

cuit and a printer magnet circuit whereby the transmitter contact circuit of one printer may be employed for operating both of the printer magnet circuits of the printers or in which the transmitter contact circuits of the respective printers may be selectively employed for operating only the printer magnet circuit of the opposite printer for duplex operation of the system.

Other and further objects of my invention reside in a convertible duplex-simplex printing telegraph system as set forth more fully in the specication hereinafter following by reference to the accompanying drawing which diagrammatically and schematically illustrates a preferred embodiment of the system of my invention.

My invention is directed to a printing telegraph system in which the capacity during hours of rush business may be doubled. The system may be operated through the usual concentrator boards, and motors on the automatic printers may be controlled in the customary manner. However, instead of the usual one-way operation normally employed in simple printer circuits, I provide means whereby, in hours of rush business, the circuit may be converted to differential. duplex operation independently of the balancedV condition of the circuit f or simplex operation and business passed simultaneously in both directions over the line wire'system. Such conversion of *5 5 the system selectively and instantaneously from l simplex to duplex permits rush of business to be disposed of promptly and economically. After the accumulation of business has subsided, the l system may be readily switchedv back to simplex 10 operation prepared for instantaneous conversion to duplex operation as conditions demand.

Referring to the drawing in detail, I have indicated an interconnecting automatic printer circuit comprising an installation at a central oilice` marked A, interconnected with an installation at a branch oflice marked B. 'The automatic printer installations are adapted to be mounted on suitable operating tables, which carry the sevv eral parts of the equipment which I have sche- 20 I matically indicated. The automatic printer atA central station A, has been illustrated as comprising a transmitting keyboard I, adapted to operate start-stop contacts 2 for the transmission of signal impulses representing the numbers and characters adapted to be transmitted from central station A. The automatic printer at station A, includes the set of magnetic windings 3, controlling the mechanical printer through movable armature, indicated at-II. Associated with the transmitter contacts 2, and the mechanical windings 3, I provide a double throw multiple poleswitch 5. The switch 5 includes a multiplicity of pivoted arms, which I have indicated at 6, T, 8 and 9, interconnected by an insulated member I0, which is pivoted centrally at each of the arms 6, 1, 8 and 9. The central switch arms are movable to either of two limiting positions at the right or left. In the right hand position, illustrated in full lines, switch arms 6, 1, 8 and 9, establish connection with contacts II, I2, I3 and i4. In'fthe other limiting position, that is, toward the left, switch'arms 6, l, 8 and `9 establish connection with contacts I5, I6, II and I8. For the purpose of explaining my invention, it will be noted at this time, that the right hand positionvof the multiple pole switch is the simplex operating position, the position now illustrated in full lines, whereas the left'hand position of the switch is the duplex operating position,

Referring now-to the branch station B, it will be seen that an automatic printer 85 is provided which is similar to the printer at central sta,- tion A, in that it includes a transmittercontactY circuit 86 and a printer magnet circuit 41. A.

break button switch 48 is provided in circuit with the transmitter contact circuit 86, for opening the line for purposes of signaling the central station A, through the connection to ground 49.

A polarized relay 50 is provided, having actuating windings 5I-52 and 53-54 similar to the actuating windings of the polarized relay at central station A. A switch 55 is provided at station B, corresponding to switch 5 at station A. Switch 55 includes movable arms 56, 51, 58'and 59 interconnected by insulated member 68, centrally pivoted to the switch arms for the purpose of shifting the switch arms simultaneously to either of -two limiting positions. The position shown in full line to the right is the simplex operating position. When moved to the left, the switches are disposed in duplex operating position. 'Ihe sets of contacts utilized for the simplex operating position of the switch are designated at 6I, 62, 63 and 64. The contacts which are employed for the duplex operating position of the switch are represented at 65, 56, 61 and 68.

Relay bias circuit at central station A is volts through resistance 34, switch arm 8, contact I3, coil 36-31 of relay 24, resistances 38 and 39 to ground 48 at approximately .030 amp. Relay bias at branch station B is 110 volts through resistance 69 dividing into two circuits, one through resistance 18to ground 49, the other through resistance 1I, coil 5I-52 of relay 58, switch arm 58, contact 63, to ground 12, coil 5I52 receiving approximately .030 amp. A direct current source, such as a battery or a generator I9, is provided at central station A.

In simplex operation, the source I9 supplies line current. The signal circuit then connects from source I9 through resistance 2I, contact I4, switch arm 9, transmitter contacts 2, coil 22-23, concentrator board 25 to line 26, thence through motor control relays 16, contact 64, switch arm 59, coils 54-53, transmitter contacts 86, closed switch 48 to ground at 49, at approximately '10 milliamperes. Contacts 2 and 86 may be used alternately to transmit signals which are printed at both stations as the current impulses pass through coil 53-54, and coil 22-23.

As source I9 alone supplies line current during simplex operation, the polarity of the source I9 with respect to source 46 at station B is immaterial. In duplex operation, however, the polarity of the sources I9 and 46 must be thesame so as to maintain the line at a neutral potential. I have shown positive potential applied to the system, but it is entirely possible to reverse the polarity and provide negative potential provided both pairs of relay contact leads are iirst transposed (11-19 and 223-33). The source I9, at central station A, connects to ground -28`at one side, and through resistance 2| to switch contact I4 at the other side. When switch 5 is thrown to the right, as illustrated, switch arm 9 provides a conductive path from contact I4 through transmitter contacts 2 and winding 22-23 of the polarized relay 24, through concentrator board 25 to the line 26.

The printer magnet circuit at station A, which includes magnetic windings 3, is actuated from the source I9, and controlled through tongue 21, and the contact 28 of the polarized relay 24. One side of the selector magnet 3, connects to contact 28. The other side of the selector magnet 3, connects to ground 29. A circuit for reducing sparking at the relay make and break, is provided in shunt with tongue 21 and contact 28, including resistance 39 and condenser 3|. A resistance 32 is connected in the circuit from the power source I9. The local circuit, through selector magnet 3, is complete through ground connections 20 and 29.

either contact 11 or contact 19 of relay 50, through switch arm 58, printer magnet windings 41, and ground connections 49 and 45. The printer magnets at stations A and B are thus operated through the relays 24 and 5I), respectively, and not directly from the line.

In describing now the duplex operation of the system, the switches 5 and 55 will be assumed to be thrown to the left hand positions. It will be noted that the polarities of the sources I9 and 46 are alike, as required, and that in duplex operation, the motor control relays at 16 are disconnected and the bias circuits are incorporated in the duplex system. In the duplex arrangement, it will be further noted, the transmitter contacts 2 and 86 are both connected with ground at one side.

Considering closed circuit conditions prevailing with both terminals idle, the circuit at station A may be traced from source I9 through resistor 34, to switch arm 8. Switch arm 8 is movable toeither of two positions. In the position shown, which is the simplex position, the circuit is complete as a simple bias circuit from contact I3 through winding 36-31 of the polarized relay 24, returning through resistance 38 and through resistance 39 to ground 48, returning to source I9 through ground 28. When switch 5 is moved to duplex position, switch arm 8 is shifted to contact I1. The circuit then continues through contact I1, branches into one path through resistance 39 to ground 48, and another through resistance 38' and winding 31-36 of polarized relay 24, connected to contact arm 1, which is resting on contact'IS. Beyond I6, the circuit is joined by the path through contact arm 6, resting on contact I5, and through resistance 4I from one side of the source I9, andY connects through lead 42, transmitter contacts 2, lead 43, and switch 9 to ground at 44. Both transmitter contacts 2 and 86 being closed, the line 26 is grounded at both ends, and is neutral, and no current flows through coil 22-23 to the line.

The corresponding conditions at station B are asV follows. The source 46 .connects through resistance 69 dividing through two paths, the one through resistance 10 to ground 49, and the other through resistance 1I through relay winding 5I-52 of polarized relay 56 to switch arm 58. In the simplex operating position,` the circuit is complete as a simple bias circuit through contact 63 and ground 'I2 to ground 45 returning to source 46. In the duplex operating position, with contacts 2 and 86 closed, the circuit continues from arrn 58, contact 81, through resistance 13, through lead 83, and is joined here by another circuit comprised of lead 14, contact arm 51, contact 66, resistance 15, connected to one side of source 46. The combined circuits are cornpleted through the transmitter contact Acircuit 86, break button switch 48, and ground 49. No current flows through winding-53-54 because the line circuit 28 is neutral. Both windings 5I-52, and 31-36, at stations B and A respectively, receive the marking current.

As indicated, I employ the motor control relays shown generally at 16 for simplex operation only, though provision may easily be made for motor control relays in the duplex circuits. `Relay 56 operates printer magnet 41 through conduplex circuits, as will be clearly understood as the description progresses.

The local printer magnet circuit for station B includes resistance 80, which is connected at one side to source 46, and at the other side to tongue 18 of polarized relay 50, operative between contacts 11 and 18. The spark reducing circuit, which includes resistance 8| and condenser 82 is effectively connected in shunt with the contacts which are in actual use during any given operating period.

Tracing the circuits through the two stations connected for duplex operation, it will be clear that when both transmitter contact circuits 86 and 2 are open, the current conditions at central station A are: 110 volts source I9, through resistance 4I, switch contact I5, switch arm 6, switch contact I6, switch arm 1, winding 36-31 of polarized relay 24, resistance 38, joined here by another circuit comprising contact I1, switch 2m arm 8, resistance 34, connecting to source I9,

thence combined through resistance 39 to ground 40. Inasmuch as line 26 is neutral, there is no current flow through winding 22--23. At the branch station B, the circuit may be traced from a@ the 110 volt source 46, through resistance 15,

contact 66, switch arm 51., conductor 14, lead 83, resistance 13, contact 61, switch arm 5B, winding 52-5! of polarized relay 50, resistance 1I, joined here by 110 volts from source 46 through A,resistance 69 and thence through resistance 10 to ground 49. There is no current in winding 53-54 of polarized relay 50. The windings 52-5I and 36-31 of the respective relays 50 and 24 are both passing spacing current, with @the contacts at 2 and 86 open.

5switch arm 51, contact 66, and resistance 15,

and thence through windings 53 and 54 of relay 58, switch arm 59 and contact 68 to line 28. That is to say during duplex operation the motor control relays 16 are shunted out. The winding 55v5I-52 of polarized relay 50, receives a small spacing current, while winding 53-54 receives a large marking current causing the relay to be marked.

At the central station A the same conditions prevail as described for both transmitter contacts 2 and 86 closed, with winding 36-31 receiving marking current, excepting that Wind-- ing 23-22 of polarized relay 24 now receives the current from line 26, terminating in ground through transmitter contacts 2, conductor 43, switch arm 9, contact I8 and ground 44. The winding 23-22 of relay 24 receives the same current value as is passed through winding 53-54 of polarized relay 50, but in reverse order, being spacing in polarized relay 24.

Exactly the same conditions occur when transmitter contacts 2 at station A are open, and transmitter contacts 86 at station B are closed, except that circuit conditions are reversed end for x end.

All that is necessary in converting the systemv from simplex operation to duplex operation, is to Y shift switches 5 and 55 from the right to the left, which may be very quickly accomplished, allowing traflic to flow in opposite directions over the line 26 simultaneously.

I provide a jack switch 84 for establishing connection with the local circuit of printer 85 for taking local copy if desired.

I have found the following values of different elements in the system of my invention particularly eflicient:

26 line resistance approXimately 1000 ohms 73 21 resistance-- 600 ohms r15-41--80--82 do' 1500 ohms 70-39 do 800 ohms 38 do| 1000 ohms 81-30 do 150 ohms '11 do 400 ohms 69-34 do 2000 ohms 82-31 condenser capacity Y l@ mf.

The following table indicates the current conditions in atypical installation embodying my invention: l

Key Current values in milliamperes observed at tation A Bias Winding Line winding Total Station Station B A Mark Spac- Mark- Spac Mark Spac ing ing ing ing ing ing Closed Closed. 20 0 0 20 Do... Open.. 8 40 32 Open Closed 20 40 20 Do Open.. 28 28 Thus, it will be seen that the marking impulses at the receiving station, in duplex operation, are the result of a differential of current in the Windings of the polarized relay. In line l of the above table of current values, therefore, a marking current of 20 milliamperes is effective at the receiver (station A) though no line current is flowing. The same holds true for the spacing impulse in the last line. In each of these instances the bias winding becomes the actuating Winding for recording the signal impulse. In each of the intermediate two lines of the table, the signal current is the differential of the line and. the bias currents; and, in this example, is effective through the line winding of the relay.

I have found the system of my invention highly practical, eflicient and economical. While I have described my invention in one of its preferred embodiments, Irealize that changes and modifications may be made, and I accordingly intend no limitations upon my invention other than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by yLetters Patent of the United States is as follows:

1. A convertible duplex-simplex printing telegraph system comprising va single line wire circuit, printing telegraph sets located at spaced intervals along said line wire circuit, each of said printing telegraph sets including a printer magnet circuit, and a transmitter contact circuit, relays interconnecting said circuits with the single line wire circuit, switching means connected with said relays, said printer magnet circuits and said transmitter contact circuits, said switching means being movable to either of two limiting positions for. causing in one limiting position the transmitter contact circuit of one printer set to be effective through said relays on the printer magnet circuit of both of said sets, and in the other limiting position the transmitter lcontact circuit of one printer set to be eiective through said relays only on the printer magnet circuit of another of said printer sets, through said single line wire circuit.

2. In a convertible duplex-simplex printing telegraph system, a pair of intercommunicating printer telegraph sets each including a printer magnet circuit and a transmitter Contact circuit, a single line wire circuit for interconnecting said sets, and means for selectively operatively relating the transmitter contact circuit of one printer set with the printer magnet circuits of both of said printer telegraph sets under one condition and selectively operatively relating the transmitter contact circuit of either of said sets exclusively with the printer magnet circuit of the opposite printer set under another condition, through said single line wire circuit. 3. In a convertible duplex-simplex printing telegraph system, a pair of intercommunicating printer telegraph sets each including a printer magnet circuit and a transmitter contact circuit, a single line wire circuit for interconnecting said sets, means for selectively operatively relating the transmitter contact circuit of one printer set with the printer magnet circuits of both of said printer telegraph sets under one condition and selectively operatively relating the transmitter contact circuit of one of said sets exclusively with the printer magnet circuit of the opposite printer set under another condition, and resistances disposed in said circuits for balancing for operation all of said circuits independently of the arrangement effected by the said last mentioned means.

4. In a convertible duplex-simplex printing telegraph system, a pair of intercommunicating printer telegraph sets each including a printer magnet circuit and a transmitter contact circuit, a single line wire circuit for interconnecting said sets, and a multi-pole switch individual to each of said printer sets and connected with said circuits, said switches being movable to either of two limiting positions for operatively relating in one limiting position the transmitter contact circuit of one printer set with the printer magnet circuits of both the printer sets and. operatively relating in the other limiting position the transmitter contact circuit of either printer set exclusively with the printer magnet circuit of the opposite printer set, through said single line wire circuit.

5. In a convertible duplex-simplex printing telegraph system, a pair of intercommunicating printer telegraph sets each including a printer magnet circuit and a transmitter contact circuit, a single line wire circuit for interconnecting said sets, a multi-pole switch individual to each of said printer sets andconnected with said circuits, said switches being movable to eitherof two limiting positions for operatively relating in one limiting position the transmitter contact circuit of one printer set with the printer magnet circuits of both the printer sets and operatively relating in the other limiting position the transmitter contact circuit of one printer set exclusively with the printer magnet circuit of the opposite printer set, and means for balancing for operation all of said circuits independently of the position of said switches.

v 6. In a convertible duplex-simplex printing telegraph system, a pair of intercommunicating printer telegraph sets each including a printer magnet circuit and a transmitter Contact circuit, a single line wire circuit for interconnecting said sets, a multi-pole switch individual to each of said printer sets and connected with said circuits, said switches being movable toi either of two limiting positions for operatively relating in one limiting position the transmitter contact circuit of one printer set with the printer magnet circuits of both the printer sets and operatively relating in the other limiting position the transmitter contact circuit of one printer set exclusively with the printer magnet circuit of the opposite printer set, and resistors disposed in said circuits for balancing for operation all said circuits independently of the position of said switches.

7. In a printing telegraph system, including a single line Wire circuit, printing telegraph sets connected with said line wire circuit in coacting relation, means for operating said sets simplex, means for operating said sets duplex, and means separately connected with each of the aforesaid means for altering the coacting relation of said sets in connection with said single line wire circuit for rendering either of said means operatively eiective at different times.

3. In a printing telegraph system for single line operation, an arrangement for duplex operation which comprises a transmitter Contact circuit and a printer magnet circuit at each of two stations, each transmitter contact circuit being connected with said line, and means for controlling the printer magnet circuit at either station by the coaction of the transmitter contact circuits at both stations through said line.

9. In a printing telegraph system for single line operation, an arrangement for duplex operation comprising a transmitter contact circuit and a printer magnet circuit at each of two stations, each transmitter contact circuit being connected with said line, means for actuating the printer magnet circuit at each station from the transmitter contact circuit at the respective station, and means for controlling the transmitter contactcircuit at one of said stations and correspondingly controlling the printer magnet circuit at the same station by the transmitter contact circuit at the other of said stations through said line.

l0. In aprinting telegraph system for single line operation, an arrangement for duplex operation comprising a transmitter Contact circuit and a printer magnet circuit at each of two stations, a polarized relay at each station adapted to control the respective printer magnet circuit, each said relay including a pair of diiierentially wound coils, means for connecting one coil of each said relay with the respective transmitter contact circuit, and means for connecting the other coil of each said relay with both said transmitter Contact circuits, whereby each said relay is actuated by the differential of two currents, one in each of said coils.

1l. In a printing telegraph system for single line operation, including a transmitter contact circuit and a printer magnet circuit at each of two stations, each transmitter contact circuit being connected with said line, means for operating said stations simplex by directly controlling the operation of both said printer magnet circuits by either of said transmitter contact circuits through said line, means for operating said stations duplex by controlling the operationfoi usv either of said printer magnet circuits by the caction of both said transmitter contact circuits through said line, and means for rendering either of said means operatively effective at different times.

12. In a printing telegraph system for single line operation, including a transmitter contact circuit and a printer magnet circuit at each of two stations, a polarized relay at each station adapted to control the respective printer magnet circuit, each said relay including a pair of differentially wound coils; means for operating said stations simplex, comprising means for biasing one coil in each said relay, and means for controlling the operation of both said printer magnet circuits by either of said transmitter contact circuits through the other coil of each said relay; means for operating said stations duplex, comprising means for connecting the bias coil of each relay with the respective transmitter contact circuit, and means for connecting the other coil of each relay with both said transmitter contact circuits, whereby each said relay is actuated by the differential of two currents, one in each of said coils; and multi-pole switching means at each of said stations for cooperatively effecting a change from simplex operation to duplex operation or vice Versa.

13. In a printing telegraph system for single line operation, an arrangement for simplex operation comprising a transmitter contact circuit and a printer magnet circuit at each of two stations, and a polarized relay at each station adapted to control the respective printer magnet circuit, each said relay including a pair of differentially wound coils; and separate switching means in circuit with one of the relay coils, said transmitter contact circuit, and said printer relay circuit at one of said stations, and with one of the relay coils, and said transmitter contact circuit at the other of said stations, for altering said arrangement for simplex operation to facilitate an arrangement for duplex operation.

14. In a printing telegraph system for single line operation, an arrangement for duplex operation as set forth in claim 10, and separate switching means in circuit with the first said relay coil, said transmitter contact circuit, said printer relay circuit, and the first said means at one of the stations, and with the rst said relay coil, said transmitter contact circuit, and in plurality in the rst said means at the other of the stations, for altering said arrangement for duplex operation to facilitate an arrangement for simplex operation.

15. In a printing telegraph system, an arrangement for duplex operation comprising a transmitter contact circuit and a printer magnet circuit at each of two stations, means at each station for controlling the respective printer magnet circuit, each said means constructed to be operative by the differential of two currents, means for producing said currents, one a bias current supplied locally, and the other a signal current controlled bythe transmitter contact circuit at the remote one of said stations, and means for balancing in the rst said means the signal current controlled by the local transmitter contact circuit.

16, In a printing telegraph system, an arrangement for simplex operation comprising a transmitter contact circuit, a printer magnet circuit at each of two stations, and means at each station for controlling the respective printer magnet circuit, each said means constructed to be operative by the differential of two currents, and means for producing said currents, one a bias current supplied locally, and the other a signal current controlled by the transmitter contact circuit at either of said stations; said arrangement including switch means connected with said circuits and with the last said means for applying other currents to the aforesaid means for varying the operation of said system.

17. In a printing telegraph system, a transmitter contact circuit and a printer magnet circuit at each of two stations, means at each station constructed to be operative by the differential of two currents for controlling the respective printer magnet circuit, and separate means at each station for selectively providing the two currents effective on the aforesaid means for determining the nature of the differential currents in regard to the respective transmitter contact circuits for establishing the character of operation, simplex or duplex, of the system.

I JOSEPH N. LOOP. 

